In some widespread and size evolving organizations, like a campus, it is necessary to structure the telecommunication system in a modular way and to maintain the different remote modules of that system functionally interconnected.
Furthermore, everything has to stay transparent for the system manager and the installer, as well as the end users, with no difference for interfaces of main and satellite modules, and the same level of features and performances should be provided by all of the modules or cabinets forming the system.
The easiness to spread the different cabinets or modules on the campus, by taking these conditions into account, is an important factor for the end price of the chosen solution and the search for a seamless (transparent) installation and operation (with no distinction) between the main and the secondary modules seems to be the most promising approach.
The above-mentioned technical problem appears in the design of private automatic branch exchanges (PABX), as well as when connecting wireless base stations (for example wireless systems using DECT technology).
It is known, from prior art, to use several types of links, and corresponding specific interfaces, to perform full connection between the various modules, i.e., a specific link for voice/data transmission, another one for signaling, another one for synchronization and still another one for resetting purposes, which requires many cables to realize the connections.
It is also known to combine some of the previous links in order to reduce the number of connecting wires, but no global solution exists.
Thus, a digital tie line for voice/data and signaling has been proposed. However, such a line implies the use of a network protocol and, consequently, a distinction will be made between the subscribers connected to the different modules.